7 Answers
7

We're looking for long answers that provide some explanation and context. Don't just give a one-line answer; explain why your answer is right, ideally with citations. Answers that don't include explanations may be removed.

Im not sure I understand your question. But it made me think of this fictitious islands and time periods (well maybe not so fictitious time periods) metal map created by Patrick Galbraith
also there are several of those types of maps in this question as answers.
If it is data you are wanting you might explain the use (after you get it into openlayers). There is a dataset put out by safe software called interopolis with the data strewn throughout the website on different training links.

Safe software has done some work with minecraft (James Fee) and many of the 3d datatypes.
Recently discussed at the user conference was the fact that Mojang had an initiative called block by block. encouraging young planners to redesign their communities to show what they would like to see it look like. It doesn't look to me they were very encouraged.

I doubt the data is readily available but since you specifically mention Discworld, there is an iOS app for the map of Ankh-Morpork which would have in in-game coordinate system and could thus be projected.

The Disc would be particularly difficult to map as you would have to write an entire spatial reference specifically for it that instead of a spheroid used a cylinder. Unless you want to consider the Disc as pancake shaped in which case converting the math so its just a smashed sphere might be easier (with The Hub being a feature on the surface not part of it, that math would be horrible). All coordinates would be polar. Most fantasy doesn't get into the details of the physical geodesy of world(s) involved so projection is not easy. Sci-fi would be more likely to be a genre with that sort of data but I don't know of anyone creating datasets for any works. I would gladly help with a Discworld project though.